Turbochargers have been extensively used in automobiles since they can further enhance the performance of an engine. The turbocharger includes a housing, and a turbine shaft supported in a center hole in the housing through bearings. In such a conventional turbocharger, the bearings are supplied with engine oil to be lubricated. Therefore, many holes serving as passages for engine oil are formed in the small housing of the turbocharger as described in Patent Literatures 1 and 2.    Patent Literature 1: JP-A-5-141259 Publication    Patent Literature 2: JP-A-10-19045 Publication